DESCRIPTION: The overall objective of the proposed collaborative study between the University of Pittsburgh, USA and the Chittaranjan National Cancer Institute at Calcutta, India is to determine the effect of non-B HIV-1 strains presumably present in Calcutta on CD+ T cell mediated suppression of HIV-1. This study is an extension of a parent grant of the principal investigator to determine the mechanism of CD8+ T cell mediated suppression of HIV-1. Specific aims of the study are to determine the sero prevalence of HIV-1 and to identify HIV-1 infected subjects among commercial sex workers, subjects attending STD Clinic and paid blood donors in Calcutta. 2. To determine the genotypes of HIV-1 present in PBMC from infected subjects from Calcutta by HMA and DNA sequence analysis of the V3-V5 region of the envelope and 3. To compare the level of CD8+ T cell mediated suppressive activity against HIV-1 strains isolated from Calcutta and the US using the investigator's developed semi-quantitative assay for suppression. The proposed study of evaluating antiviral activity of CD8+ T cells against HIV-1 strains of various clades will be extremely important for determining the mechanism of CD8+ T cell mediated suppression of HIV-1. In addition, the information obtained from the proposed study would be useful in the development of an HIV-1 vaccine which ideally would be expected to induce CD8+ T cell mediated suppression against HIV-1 of all clades.